Permanent mold



July 26,1938. M. A. BECKMANN PERMANENT MOLD Filed June 18, 1936 N W MM 1 "A r m z Attorney Patented July 26,

PATENT OFFICE 2,124,998 PERMANENT 'MoLn' Melbourne A. Beckmann, Cincinnati Ohio, r signor to Aluminum Industries, Inc., Cincinnati.

Ohio, a corporation of Ohio Application June is, 1936, Serial No. 85,946

4 Claims.

The present invention relates to a permanent mold particularly adapted to cast pistons in aluminum alloys which pistons are described and shown in my co-pending ,applications, Serial Nuxibers 79,309, 79,310 and,.79,311, flied May 12,

The casting of pistons in permanent molds is complicated by the necessity of lifting out the cores bodily. In the ordinary piston, the pin cores, but in, the pistons here considered,- the bridge forms an additional obstacle; The

means provided for casting this bridge and for providing for the removal ofth cores entire from about and within the bridge iorni the subject matter of the invention. One of its objects-is to provide such an arrangement of cores that a piston of my special kind' can. be produced expeditiously from a mold or the general 20 type described in the United States patent to Schnobrich, No. 1,525,893 of February 10, 1925.

Another object is to provide means for keeping the thickness of the bridge metal in properr'e- In the accompanying drawing, Figure 1 is a vertical cross section or the mold with all or the cores in place except the bridge core, which is shown above its proper place. The cores are shown in section along the line' oi Fig. 4.

Figure 2 shows all of the cores except the piston pin cores, assembled, partly in section on the line 2-2 of Fig. '4.

Figure 3 is a perspective cross-sectional view of a piston to be cast in my mold. tion between Figures 2 and 3 is as-ii the cores ofFigure, 2 had'flrst been pulled out or the piston of Figure 3, and reassembled. immediately a ve.

4 Figure 4 is a cross section of the entire central .40 core assembly taken on the line 4-4 of Figure 2. In Figure 1, I0 is the body of the niold, II is the floor and I2 is the mold cavity. This cavity is established in the form of an inverted internal combustion engine piston by aseven piece core 4 which may be considered to be composed of two kinds of pieces. cores l3 which extend into the mold cavity from opposite sides, and the 'core pieces II, I8, I! and 2|, shown assembled in Figure 2, which extend vertically from aboveinto the mold cavity. These are preferably -flve in number-but may be more or less insome cases.

Thedepending cores are each provided with an upper flange l5 each of which-is so shaped as to tit and cooperate with the other flanges l5 bosses are the only obstacle to lifting out such around it. Accurate control of the shape and thickness oi the bridge is thus'rendered possible The rela- These are the piston pin hole because no substantial displacement of core 2| also manipulated as in the patent referred to.

Each core, except I3 is provided with an individual handle |6 for manual withdrawal.

, Referring to Figure-4, the central core assembly. comprises a core I! of nearly rectangular l0 cross section. This is the largest core and the one which is last inserted and first withdrawn after casting. Flanking the core ll there are two irregularly shaped side cores l8. Abuttin all three of the just mentioned cores there is a. 15 butterfly core" |9,"so called because its cross section looks from above like a butterfly minus the body. Another core 2|, known as-the bridge core, because its function is to help form the bridge 24, shown in Figure 3, is contained within the butterfly core. Its upper portion as seen in Figure 2, is completely encircled by the core I! so that it is firmly positioned, but its lower end 2| hangs free so that the metal can flow because the core is aligned not only by the top flange l5 but also by a long-bearing surface 20 cooperating with the core It. The former controls the depth and the latter the alignment. The coresurfaces are allaccuratelymachined in cast iron, so that close fitting is, achieved.

In operation the cores l8 are inserted first in the empty mold; the piston pin hole cores l3 which formthe piston. pin holes 22 and the bosses 23 around them are then brought into position. Core i9 isthen inserted and the bridge core 2| slipped into it. Core i1 is now positioned and the casting performed. I

Ai'ter setting of the metal, core 2| is usually first pulled, then cores l1 and I9, althoughco're I! may be pulled flrst; cores, l8 can then be .withdrawn by pulling them flrst'to. the middl of. the mold cavity until they clear the bosses, then lifting upward;

By having the bridge core suspended in the butterfly core on a long, accurate bearing, ;even if the butterfly core should become somewhat misaligned'in relation to cores H or IS, the bridge casting would still be strong and accurate in core I! is possibles I claimas my invention: 1 l. A permanent-mold structure for making a internal combustion engine piston which com- 56 prises a moldbody two piston hole excomprising a mold body and av multiple piece core fitting into said body, one of saiducore piecesxcontaining another, said contained piece being held over a portion of its length at a distance from its containing core, and being ex- 7 tractable therefrom so that said containing core may be withdrawn from the mold.

3.-A mold. core for a permanent mold metal 2. A permanent mold metal casting structure 7 "al a-gees casting structure composed of at least two core pieces, one core piece being contained within the other and spaced theretrom'over a portion of its length and being extractable-theretrom-so that said containing'coremay be withdrawn from the mold. I

4. A mold core for a permanent mold metal casting structure composed of at least two core pieces, one eel-e piece being contained within the other and spaced therefrom over a portion of its length and being extractable therefrom so. that said containing core may be withdrawn from the mold, a portion of said containing piece being cut out around saidcontained piece to permit molding material to -flo,w therebetween.

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